Earlier this year, I wrote an article titled “What type of respirator do I need?” in which I explained how respirator users and administrators can use data to determine the proper type of respiratory protection that would be needed. But this article was written under the assumption that the user/administrator had the most essential piece of data… the level of the contaminant. This article helps explain what OSHA says in their May 2012 Letter of Interpretation regarding air sampling and respirator use.
Although the LOI was written specifically to using methylene biphenyl isocyanate (MDI), the rationale and methodology fit any contaminant. It is disturbing that OSHA has now formally stated that an employer does not need DEFINITIVE DATA to determine the level of respiratory protection for the workers and that OBJECTIVE DATA can be used instead. I wholeheartedly disagree with this, but OSHA has set the bar.
OSHA states in the LOI that acceptable methods include, but are not limited to, using objective data, applying mathematical approaches, and others. Using objective data is when the employer uses data obtained from industry studies, trade associations, or tests conducted by chemical manufacturers, which demonstrate that air contaminants cannot be released in the workplace in airborne concentrations that are IDLH. The objective data must represent the highest contaminant exposures likely to occur under reasonably foreseeable conditions of processing, use, or handling, and the respirator administrator must document the use of this objective data as part of the written Respiratory Protection Program.
The preamble to the final rule (p. 1199) states that employers can use data on the physical and chemical properties of air contaminants combined with information on room dimensions, air exchange rates, contaminant release rates, and other pertinent data including exposure patterns and work practices to estimate the maximum exposure that could be anticipated in the workplace. This is the “mathematical approach” OSHA is referring to.
Additional information regarding hazard evaluation can be found at CPL 02-00-120, Inspection Procedures for the Respiratory Protection Standard, paragraph E.
When using any of these methods, the data needs to be accurate and representative of conditions at the current work site, including materials being applied and work being performed. In addition, the assessment would also need to consider exposures to any other hazardous chemicals.
Referring back to my earlier article, I stated there are four pieces of data that the user/administrator MUST have in order to determine the level of respiratory protection. #1 is to know the chemical(s) involved and #2 is to know the concentration of the chemical(s) involved. Even if we know the chemical(s) involved, without knowing the concentration (e.g., the exposure), we can not be certain that workers are not being overexposed to the contaminate(s)!
Here is the OSHA LOI…